for all those with surging idles...long

avbcon12 · 05-09-2002, 07:14 PM

well, i just got to the root of my surging upon startups. i have been trying to tune everything possible in order to get rid of it. i knew my fuel pressure and timing were right on the mark...

so i then began to think that it had to be mechanical. i started to think about how i had my PCV system now then when my idle was smooth.

i had put a breather in place of the oil cap!

so then i was thinking that since i had the PCV still hooked up in the back of the intake there had to be a huge vacuum loss because i didnt have the tube that goes from the throttle body to the oil neck anymore. the PCV was just pulling air in through the breather i had put on. there was a HUGE vacuum loss!!

what i did was instead of putting the tube back on that goes to the throttle body. i just put a airflow control valve inline of the PCV. so i could keep the vacuum down so it wouldnt be such a huge loss, yet keep enough to evacuate the crankcase gasses.

that little valve solved ALL of my idle problems.
i just wanted to let you guys know because i know there are a lot of people out there that have idle problems...

hope it helps,
adam

gtsr515 · 05-09-2002, 07:21 PM

Your problem was caused by unmetered air introduced into the engine, the result of the open oil breather.

avbcon12 · 05-09-2002, 07:44 PM

exactly!

thanks,
adam

MidNiteBlu 5.0 · 05-09-2002, 08:12 PM

I just put one of those breather caps with a filter and i havent noticed any difference in performance or drivability. I left the tube on though. Are you not sopposed to put breather caps on an efi engine? I just did it because it looks cool lol.

Later,
Nick

avbcon12 · 05-09-2002, 08:18 PM

well, thinking about how you have yours setup. you have a loss in vacuum too. because the PCV system is then open to the atmosphere and not being metered. i dont know how you are not experiencing any problems....

take care,
adam

Mach 1 · 05-09-2002, 09:04 PM

I have tried replacing the oil cap instead of the breather to cure a surging idle problem, and it didnt change anything. Im glad this fixed your car, but I dont think its the answer for everybody.

avbcon12 · 05-09-2002, 09:20 PM

im not saying it is, just trying to give other people ideas...

adam

05-09-2002, 07:14 PM	#1
avbcon12 Registered Member Join Date: Jul 2001 Location: West Bloomfield, MI Posts: 391	for all those with surging idles...long well, i just got to the root of my surging upon startups. i have been trying to tune everything possible in order to get rid of it. i knew my fuel pressure and timing were right on the mark... so i then began to think that it had to be mechanical. i started to think about how i had my PCV system now then when my idle was smooth. i had put a breather in place of the oil cap! so then i was thinking that since i had the PCV still hooked up in the back of the intake there had to be a huge vacuum loss because i didnt have the tube that goes from the throttle body to the oil neck anymore. the PCV was just pulling air in through the breather i had put on. there was a HUGE vacuum loss!! what i did was instead of putting the tube back on that goes to the throttle body. i just put a airflow control valve inline of the PCV. so i could keep the vacuum down so it wouldnt be such a huge loss, yet keep enough to evacuate the crankcase gasses. that little valve solved ALL of my idle problems. i just wanted to let you guys know because i know there are a lot of people out there that have idle problems... hope it helps, adam __________________ 90 GT black/ grey leather ported GT-40 heads w/ 1.7RR, Cobra intake w/ ported lower, 24# injectors, 190LPH pump, 75mm Pro-M MAF, 65mm TB, K&N panel, BBK long tubes, Off road H-pipe, 2 ch. Flowmaster, Black magic fan, Kirban FPR, 180 deg. T-stat, 3.73's, Steeda Tri-Ax, 130 amp alt. Accell 8.8 race wires/cap/rotor, motorcraft plugs, Factory Five suspension, etc etc etc.... http://avbcon12.stangnet.com

05-09-2002, 07:21 PM	#2
gtsr515 Registered Member Join Date: Nov 2001 Location: Sunny, Hot, Sebring, Florida Posts: 725	Your problem was caused by unmetered air introduced into the engine, the result of the open oil breather. __________________ Remember...2nd place is 1st place for losers!

05-09-2002, 07:44 PM	#3
avbcon12 Registered Member Join Date: Jul 2001 Location: West Bloomfield, MI Posts: 391	exactly! thanks, adam __________________ 90 GT black/ grey leather ported GT-40 heads w/ 1.7RR, Cobra intake w/ ported lower, 24# injectors, 190LPH pump, 75mm Pro-M MAF, 65mm TB, K&N panel, BBK long tubes, Off road H-pipe, 2 ch. Flowmaster, Black magic fan, Kirban FPR, 180 deg. T-stat, 3.73's, Steeda Tri-Ax, 130 amp alt. Accell 8.8 race wires/cap/rotor, motorcraft plugs, Factory Five suspension, etc etc etc.... http://avbcon12.stangnet.com

05-09-2002, 08:12 PM	#4
MidNiteBlu 5.0 I got something to say Join Date: Sep 2001 Location: San Diego, CA Posts: 1,557	I just put one of those breather caps with a filter and i havent noticed any difference in performance or drivability. I left the tube on though. Are you not sopposed to put breather caps on an efi engine? I just did it because it looks cool lol. Later, Nick __________________ 91 LX Hatch 5.0 - made for the twisties 89 LX Hatchback 5.0 5spd. stolen/stripped 4/7/05 http://www.mustangworks.com/cgi-bin/...splay.cgi?3494 1987 Toyota Pickup Ricer Haters Club Member #33 Want a custom gauge cluster for your Vintage Mustang? www.jmeenterprises.com

05-09-2002, 08:18 PM	#5
avbcon12 Registered Member Join Date: Jul 2001 Location: West Bloomfield, MI Posts: 391	well, thinking about how you have yours setup. you have a loss in vacuum too. because the PCV system is then open to the atmosphere and not being metered. i dont know how you are not experiencing any problems.... take care, adam __________________ 90 GT black/ grey leather ported GT-40 heads w/ 1.7RR, Cobra intake w/ ported lower, 24# injectors, 190LPH pump, 75mm Pro-M MAF, 65mm TB, K&N panel, BBK long tubes, Off road H-pipe, 2 ch. Flowmaster, Black magic fan, Kirban FPR, 180 deg. T-stat, 3.73's, Steeda Tri-Ax, 130 amp alt. Accell 8.8 race wires/cap/rotor, motorcraft plugs, Factory Five suspension, etc etc etc.... http://avbcon12.stangnet.com

05-09-2002, 09:04 PM	#6
Mach 1 Registered Member Join Date: May 1999 Location: Georgia Posts: 3,866	I have tried replacing the oil cap instead of the breather to cure a surging idle problem, and it didnt change anything. Im glad this fixed your car, but I dont think its the answer for everybody. __________________ 2002 GT 1993 GT (SOLD) '93 Mustang GT RHC member #142

05-09-2002, 09:20 PM	#7
avbcon12 Registered Member Join Date: Jul 2001 Location: West Bloomfield, MI Posts: 391	im not saying it is, just trying to give other people ideas... adam __________________ 90 GT black/ grey leather ported GT-40 heads w/ 1.7RR, Cobra intake w/ ported lower, 24# injectors, 190LPH pump, 75mm Pro-M MAF, 65mm TB, K&N panel, BBK long tubes, Off road H-pipe, 2 ch. Flowmaster, Black magic fan, Kirban FPR, 180 deg. T-stat, 3.73's, Steeda Tri-Ax, 130 amp alt. Accell 8.8 race wires/cap/rotor, motorcraft plugs, Factory Five suspension, etc etc etc.... http://avbcon12.stangnet.com

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